Green synthesis of gamma rays-induced melanin-based bismuth oxide nanoparticles for evaluation of the antibacterial and anti-virulence activities against extra-intestinal pathogenic bacteria.

The rise of microorganisms that are resistant to drugs is one of the significant challenges facing the health sector. The need to identify effective alternatives facing bacterial diseases is significantly highlighted. Nanomaterials have the potential to be a game-changing weapon in the battle against infectious diseases. Melanin, with the assistance of different doses of gamma rays, successfully produced highly stable BiO NPs. The most effective dose was 40 kGy. BiO NPs were characterized using FTIR, XRD, DLS/zeta potential, and TEM. In this study, the antibacterial efficacy of BiO NPs versus the extra-intestinal bacteria and was evaluated. BiO NPs at 200 µL generate inhibition zone diameters of 35.26 ± 0.305 and 38.42 ± 0.570 mm for and , respectively. BiO NPs at 200 µL caused significant biofilm reduction of 81.05 and 88.25% also, registered a significant decline in the colony count of (0.29 × 10) for and (0.15 × 10) for . The BiO NPs greatly decreased catalase activity, displaying 1.5 ± 0.62 and 6.0 ± 0.91 U/mL, and lipase activity exhibiting 12.13 ± 0.34 and 6.7 ± 0.26 U/mL for and , respectively. SEM observations indicated that the bacterial cell membrane was disrupted, resulting in significant ultrastructure alterations. BiO NPs reported a moderate cytotoxic effect on normal kidney epithelial cells with IC value of 513.9 ± 2.71 µg/mL. In conclusion, BiO NPs exhibited potential antibacterial activity, suggesting recommended usage in medical fields. The novelty of this study is the use of low-dose gamma irradiation to synthesize highly stable BiO NPs.